Biology subjects

Alvarez-Melo, D.

Publications and source records attributed to Alvarez-Melo, D..

2 recordsLinked to original sources

bioRxiv2025

Nucleolar Cdc14 Splitting Reflects Recombination Context and Meiotic Chromosome Dynamics

Chromosome dynamics, recombination, and nucleolar organization intersect during meiotic prophase I, yet how recombination context influences nucleolar architecture remains unclear. We analyzed the nucleolar pool of Cdc14 in Saccharomyces cerevisiae under matched prophase-I gating. In a recombination-competent reference (ndt80{Delta}), Cdc14-mCherry formed a predominant single focus with occasional, reversible two-focus episodes that Nop56-GFP placed within the nucleolar compartment ("nucleolar splitting"). Splitting rose sharply in dmc1{Delta} ndt80{Delta} and remained high in spo11-y135f dmc1{Delta} ndt80{Delta}, demonstrating that elevated DSB formation is not required and pointing instead to homolog-engagement state as the key variable. Population checkpoint readouts did not map onto the phenotype: Hop1 phosphorylation was strong in dmc1{Delta}, weak/transient in ndt80{Delta}, and undetectable in spo11-y135f, yet splitting was high in dmc1{Delta} and spo11-y135f and low in ndt80{Delta}. Persistence metrics showed that events concentrated early and waned in ndt80{Delta}, whereas dmc1{Delta} and spo11 backgrounds retained activity into later windows, consistently across thresholds. We propose that nucleolar splitting reflects rheological responses of a nucleolar condensate to chromosome-scale forces that vary with homolog engagement. This view is consistent with DSB-independent contributions from telomere clustering into the bouquet configuration, telomere-led rapid prophase movements, and centromere coupling/pairing as routes that shape force transmission to the rDNA territory. In this sense, the nucleolus emerges as a mesoscale, mechanically sensitive readout of meiotic chromosome dynamics.

genetics↗

bioRxiv2019

Cdc14 phosphatase ensures resolution of aberrant meiotic recombination outcomes partly through activating Yen1/GEN1

Meiotic defects derived from incorrect DNA repair during gametogenesis can lead to mutations, aneuploidies and infertility. Coordinated resolution of meiotic recombination intermediates is required for crossover formation, ultimately necessary for accurate completion of both rounds of chromosome segregation. Numerous master kinases orchestrate the correct assembly and activity of the repair machinery. Although much less is known, reversal of phosphorylation events in meiosis must also be key to coordinate the timing and functionality of repair enzymes. Cdc14 is an evolutionarily conserved phosphatase required for the dephosphorylation of multiple CDK1 targets. Mutations that inactivate this phosphatase lead to meiotic failure, but until now it was unknown if Cdc14 plays a direct role in meiotic recombination. Here, we show that elimination of Cdc14 leads to severe defects in the processing and resolution of recombination intermediates, causing a drastic depletion of crossovers when other repair pathways are compromised. We also show that Cdc14 is required for correct activity and localization of the Holliday Junction resolvase Yen1/GEN1. We reveal that Cdc14 regulates Yen1 activity from meiosis I onwards, and this function is essential for crossover resolution in the absence of other repair pathways. We also demonstrate that Cdc14 and Yen1 are required to safeguard sister chromatid segregation during the second meiotic division, a late action that is independent of the earlier role in crossover formation. Thus, this work uncovers previously undescribed functions of Cdc14 in the regulation of meiotic recombination.

genetics↗